Rotational devices, such as control moment gyroscopes, are commonly employed in satellite attitude control systems. Such rotational devices generally comprise a stationary body (i.e., a housing) and a rotational body (i.e., a rotor). The rotor may include an inertial element (e.g., outer rim) that is coupled to a rotational shaft by way of a suspension web. The shaft's upper and lower ends are each received by an annulus provided within the housing. As rotational motion is imparted to the inertial element, each shaft end rotates within its annulus. First and second bearing assemblies may be disposed within each annulus and around a shaft end. Each bearing assembly may comprise, for example, a bearing cartridge and an outer sleeve, which exerts a predetermined clamping force on the bearing cartridge. The bearing cartridge may include an inner ring, an outer ring, and a plurality of rolling elements (e.g., ball bearings) captured between the inner ring and the outer ring. As the rotor turns, the inner ring rotates along with the rotor's shaft and the ball bearings travel within the raceway thus minimizing frictional forces.
The rotor of the rotational device described above may be imbalanced, resulting in vibrations that may be imparted to, and negatively impact the performance of, the host satellite. The vibrations may be induced from static imbalance, which may occur as a result of the principal inertia axis of the rotor being offset from and parallel to the axis of rotation, and/or dynamic imbalance, which may occur as a result of the principal inertia axis of the rotor intersecting the rotation axis of the rotor at the center of mass, where the principal inertia axis and the rotation axis are not parallel. Although compliant mounts have been developed to attenuate (e.g., isolate) vibrations produced by such imbalances, compliant mounts may decrease the effectiveness of the rotational device. Moreover, compliant mounts may be relatively bulky and thus undesirably cumbersome for deployment onboard a satellite.
Considering the foregoing, it is desirable to provide a vibration reduction system that occupies a relatively small volume with relatively small mass suitable for use in conjunction with a rotating device, such as a control moment gyroscope. Preferably, such a vibration reduction system would be capable of significantly reducing vibrations resulting from both rotor imbalances and other imperfections, such as bearing geometry imperfections. It would also be desirable to provide an active bearing mount for use in conjunction with such a vibration reduction system. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.